Herbal remedies may not be all benign

December 18, 2014

Cancer patients have been warned that commonly used complementary remedies including fish oil, green tea and ginger could increase the risk to the health and undermine the effectiveness of conventional treatments.

In a presentation to the Clinical Oncology Society of Australia’s Annual Scientific Meeting, researchers at Melbourne’s Peter MacCallum Cancer Centre reported that the 10 most common complementary medicines could interfere with the operation of chemotherapy drugs, unexpectedly increasing their toxicity or reducing their effectiveness.

“These products may increase the effects of chemotherapy and put the patient at risk of toxicity, or decrease the efficacy of chemotherapy,” lead author Sally Brooks said. “Those that contain high levels of antioxidants may interfere with both chemotherapy and radiation therapy.”

The study was based on inquiries made by doctors and patients to the hospital’s Medicines Information Centre over a two-year period, and covered the 10 most common complementary medicnes, including fish oil, turmeric, coenzyme Q10, milk thistle, green tea, ginger, lactobacillus, licorice, astragalus and reishi mushroom.

Ms Brooks said these substances were unlikely to cause problems when they were consumed as part of a normal, healthy diet, but were problematic when they were concentrated in larger amounts in complementary medicines.

She said the complexity of dealing with different types of cancers, and the enormous variety of responses among individuals, meant that much more research was needed.

Nonetheless, she said, “what’s safe for one person may not be for another. We need to raise awareness of proven and potential risks”.

Clinical Oncology Society of Australia President Associate Professor Sandro Porceddu said the research was an alert for people to be careful about what they took.

A/Professor Porceddu said patients could wrongly assume that anything that was natural and labelled complementary was safe and would complement conventional cancer therapies.

“Although some complementary therapies and medicines may benefit patients, they can also be dangerous and undermine treatment,” he said. “Until we know more, it is best to err on the side of caution, and for patients to discuss with the health care provider any complementary or alternative therapies they are using or considering using.”